I have a server which I upgraded recently from 2.3.13 to 2.3.14.
Now I realized that sending mail to shared folders doesn't work anymore.
I have verified the problem on a test box and it looks like this:

May 28 11:01:49 install lmtpunix[15085]: accepted connection
May 28 11:01:49 install lmtpunix[15085]: lmtp connection preauth'd as postman
May 28 11:01:49 install lmtpunix[15085]: verify_user(system) failed:
Permission denied
May 28 11:01:49 install postfix/lmtp[15077]: 87D6F34018:
to=<+>, orig_to=<+system at localhost>,
relay=install.corp.invoca.ch[/var/lib/imap/socket/lmtp], delay=0.12,
delays=0.09/0.01/0/0.03, dsn=5.7.1, status=bounced (host
install.corp.invoca.ch[/var/lib/imap/socket/lmtp] said: 550-You do not
have permission to post a message to this mailbox. 550-Please contact the
owner of this mailbox in order to submit 550-your message, or postmaster
if you believe you 550-received this message in error. 550 5.7.1
Permission denied (in reply to RCPT TO command))

The mailbox has the following permissions:

localhost.localdomain> lam system
anonymous p
anyone lrs

I just downgraded to 2.3.13 and it works again, upgrading to 2.3.14 and it
doesnt.

Somehow there was a change from 2.3.13 to 2.3.14 which triggers the
problem. I tried to identify which change it is but can't find it.

Another interesting detail is that both servers where it doesn't work are
RedHat EL4 on i386 while I have a server RedHat EL5 on x86_64 where it
seems to work.

Does anyone who knows the changes between 2.3.13 and 2.3.14 have an idea
what could be the problem here?